Question

College Algebra: I'm doing 3X3 Linear Systems and I'm stuck on a word problem. I'm not good with word problems. Can somebody work this out step-by-step with me? The problem is:
"Stocks, Bonds, and a Mutual Fund: Marita invested a total of $25,000 in stocks, bonds, and a mutual fund. In one year she earned 8% on her stock investment, 10% on her bond investment, and 6% on her mutual fund, with a total return of $1,860. Unfortunately, the amount invested in the mutual fund was twice as large as the amount she invested in the bonds. How much did she invest in each?"

Answer 1

I'm not familiar with typing matricies. Sorry!

[1,1,1]
[.08,.10,.06]
[0,1,-2]

times

[s]
[b]
[m]

equals

[25000]
[1860]
[0]

Answer 2

It should be formatted like this
[][][] [] []
[][][] x [] = []
[][][] [] []

Answer 3

You lost me :-/

Answer 4

Let S represent the initial investment in Stocks.
Let B represent the initial investment iin Bonds.
Let F represent the initial investment in Mutual Funds.

S + B + F = 25000
.08S + .10B + .06F = 1860
F = 2B

Those are your three equations in three unknowns.

I don't know if you are supposed to solve those manually or if you are allowed to use technology.

Using technology, you can see what the results are at:

http://www.wolframalpha.com/input/?i=.08x+%2B+.10y+%2B+.06z+%3D+1860%2C+x+%2B+y+%2B+z+%3D+25000%2C+z+%3D+2y

where x is Stocks, y is Bonds, and z if Mutual Funds

@Natasha.g.2013

This problem can also be done with one equation but three equations were specified in the problem statement.